Flashcards in Quality Control Statistics Deck (28)

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1

Q

What is the definition of mean?

A

mathematical average

2

Q

What is the formula for the mean?

A

sum of all the data points divided by number of data points

3

Q

Calculate the mean of 3, 7, 7, 19.

A

= (3+7+7+19)/4

= 36/4

= 9

= 36/4

= 9

4

Q

Calculate the median of 3, 7, 7, 19.

A

= (7 + 7) / 2

= 7

in this example, because we have an even number of data points, we take the two in the middle and average

= 7

in this example, because we have an even number of data points, we take the two in the middle and average

5

Q

Calculate the mode of 3, 7, 7, 19.

A

mode is the most common observation, so the mode is 7

6

Q

What is the formula for determining percent sensitivity?

A

= # disease persons with a positive test result divided by total # Disease Persons multiplied by 100

= TP / (TP + FN)

= TP / (TP + FN)

7

Q

What is the formula for determining percent specificity?

A

= # nondiseased persons with a negative test result divided by total number of nondiseased persons multiplied by 100.

= TN / (TN + FP)

= TN / (TN + FP)

8

Q

What is the formula for determining positive predictive value (PPV)?

A

= TP / (TP + FP)

9

Q

What is the formula for determining negative predictive value (NPV)?

A

= TN / (TN + FN)

10

Q

What is the definition of specificity?

A

probability of correctly classifying a non-diseased person as non-diseased

true negative rate

true negative rate

11

Q

What is the definition of False Positive Rate?

A

probability of correctly classifying a non-diseased person as diseased

12

Q

What is the definition of sensitivity?

A

probability of correctly classifying a diseased person as diseased

true positive rate

true positive rate

13

Q

What is the formula for the False Positive Rate?

A

= FP / (TN + FP) x 100

or

= 1 - specificity

or

= 1 - specificity

14

Q

What is the formula for the False Negative Rate?

A

= FN / (TP + FN) x 100

or

= 1 - sensitivity

or

= 1 - sensitivity

15

Q

What is the formula for the total number of diseased persons?

A

TP + FN

16

Q

What is the formula for the total number of non-diseased persons?

A

TN + FP

17

Q

What is the definition of accuracy?

A

closeness of a measured value to its true value. In other words, the ability to get close to the bulls eye.

18

Q

What is the definition of reproducibility?

A

closeness of repeated measurements of the same quantity. in other words, the ability to hit the same spot on the target.

19

Q

With 'normal distribution', what is the value of observations that will make up the distribution between +/- one standard deviation?

A

68%

20

Q

With 'normal distribution', what is the value of observations that will make up the distribution between +/- two standard deviations?

A

95%

21

Q

With 'normal distribution', what is the value of observations that will make up the distribution between +/- three standard deviations?

A

99%

22

Q

What three conditions can be shown using a Levey-Jennings plot?

A

1. trend

2. shift

3. dispersion

2. shift

3. dispersion

23

Q

Describe a Levey-Jennings plot?

A

plot of control results on the y-axis versus time on the x-axis.

24

Q

What is dispersion?

A

increased frequency of both high and low numbers. the plot has values above and below the line designating 2SD.

25

Q

What is a trend?

A

progressive drift of reported values from a prior mean. the plot shows a drift consistently above or below the line designating 2SD.

26

Q

What is a shift?

A

an abrupt change from the established mean. The plot shows a very abrupt shift above or below the line designating 2SD.

27

Q

What is the number and type of patients that would be tested to establish a reference range?

A

100 patient from the local community.

Include variations in race, sex, age, weight, nutritional status, degree of physical activity, geography, time of day.

The range is established with the 95% confidence limits.

Include variations in race, sex, age, weight, nutritional status, degree of physical activity, geography, time of day.

The range is established with the 95% confidence limits.

28

Q

When were the CLIA '88 regulations published?

A

2003